By Paul Podsiadlo and Elena Shevchenko, Argonne's Center for Nanoscale Materials
This psychedelic pattern comes from a thin layer of lead-sulfide nanocrystals evaporated atop a silicon surface. The black branch is a deliberate scratch on the smooth area and creates a rough patch where crystals are more likely to form. Understanding how nanoparticles behave at the molecular level could help scientists use them in solar cells, batteries and other energy devices.
The pattern represents a film of 7.5-nanometer lead sulfide nanocrystals evaporated on the surface of a silicon wafer. The branch is formed by “supercrystals”: faceted 3-D assemblies of the same nanocrystals, crystallized in a mechanically induced scratch. The supercrystals have shown preferential nucleation in scratches. The picture is a true, unaltered image, obtained with an optical microscope in reflected light mode.
Photo courtesy of Argonne National Laboratory.